Air precleaners are frequently used with internal combustion engines of off-road vehicles, such as earth moving equipment, agricultural vehicles, and the like, which often operate in dusty environments. One common type of air pre-cleaner incorporates a group of vortex separators, which extend in parallel relation between an outer wall of the precleaner and an internal wall. Each vortex separator includes a generally cylindrical inlet tube, which is connected within an opening in the outer wall of the precleaner, and an axially aligned inner tube, that is connected with an opening in the inner wall. The downstream end of the inlet tube is spaced radially from the upstream end of the outlet tube to provide an annular clearance which communicates with a contaminate chamber between the outer wall of the precleaner and the internal wall. The downstream end of the outlet tube communicates with a second chamber which, in turn, is connected to the air cleaner for the engine.
The inlet tube of the typical vortex separator includes a plurality of vanes which cause the incoming particulate-laden air to be swirled outwardly. The heavy particulate material will swirl outwardly along the wall of the inlet tube and pass through the annular clearance to the contaminate chamber. The particulate material is scavenged from the contaminate chamber by connecting the contaminate chamber to a source of sub-atmospheric pressure, such as the exhaust system of the engine, thus drawing the particulate material out through the exhaust system.
In the typical vortex separator, the cleaner air flows along the vortex in the inlet tube, and passes through the outlet tube or nozzle and thus to the air cleaner for the engine.
It is important to provide a seal between the outlet tube of the vortex separator and the internal wall of the pre-cleaner. If the joint between the outlet tube and the internal wall is not sealed, particulate material can be drawn through the unsealed joint from the contaminate chamber to the air cleaner.
It has been the practice in the past to connect the tubes of the vortex separator to the walls of the precleaner by a two-step operation. In this procedure, an annular ridge or shoulder is formed on the tube and spaced from the tube end. The end of the tube is then inserted within an opening in the wall of the pre-cleaner to bring the shoulder in engagement with a surface of the wall. A heated die is then employed in a second operation to curl or upset the projecting end of the tube and bring the upset end into engagement with the opposite surface of the wall.
Other types of connections have used gaskets or sealants to provide a seal between the vortex tubes and the wall of the air precleaner.
The use of the two-step upsetting operation, or the use of gaskets and sealants, contribute substantially to the overall cost of the precleaner, particularly when the typical precleaner may contain up to forty or more vortex separators.